Light has properties of waves. Let's look at these properties. One of these properties is diffraction. Diffraction is a wave spreading out as it passes through a small opening or around an obstacle.

220px-Wave_Diffraction_4Lambda_Slit.png
This property is in all waves. when two or more waves go through these slits they create two interference's constructive and destructive. When two waves collide it creates destructive interference. This Destructive Interference is created by the energies of light cancelling each other out.

light as well does this as proves by thomas young in 1803.

Light also had proven to have wave properties by a man name Poisson. Poisson believed that light was a particle. To prove that it was a particle he theorized that if it truly behaved like a wave it would look like this.
doppler.gif
If this is true then if a light was shined upon a black circle onto a screen it would create a light spot in the centre. Now he never tested this but one day a man by the name of Arago. When he performed the experiment this image appeared on the screen behind it.
poissonspot.jpg
This proved that light actually does have wave properties.